Resolution of (±)-3-methylmuconolactone and the absolute configurations of the naturally occurring 3- and 4-methylmuconolactones: X-ray crystal structures of (S)-1-phenylethylammonium salts and a bromodilactone

Abstract
(%)-3-Methylmuconolactone (4c) has been resolved via the diastereoisomeric salts of (S)-(–)-1-phenylethylamine and the absolute configurations of fungal (4S)–(-)-3-methylmuconolactone (6) and bacterial (4S)-(+)-4-methylmuconolactone (9) have been determined by combined use of X-ray crystallographic analysis and chemical correlation.